The present invention is directed primarily to a series of plasticizer esters and method for making such esters for use in the formulation of polyvinyl chloride (PVC), such as phthalates, adipates and trimellitates. These plasticizer esters are prepared by the reaction of an aromatic or aliphatic diacid, triacid, or acid anhydride with an alcohol prepared by the hydroformylation of a C6-C10 olefins using a titanium, zirconium or tin-based catalyst or an acid catalyst, provided that the olefin contains at least 50% mono methyl branching at the beta carbon, e.g., 2-methyl octene-1 or 2-methyl octene-2. Such novel plasticizers have been found to be especially useful in the manufacture of low fogging, flexible polyvinyl chloride (PVC) automotive interior trim applications.
Since their introduction in the late 1960""s, esters of branched C9 alcohols have continued to gain prominence as plasticizers for PVC. PVC compounds prepared with phthalate esters of branched C9 alcohols are used in many different market segments; these include electrical wire insulation, flexible vinyl flooring, vinyl coated wallpaper, vinyl shower curtains, synthetic leather, vinyl boat covers, vinyl swimming pool liners, vinyl stationary products or notebook covers, and tarpaulins.
Esters of branched C9 alcohols are preferred over esters prepared from 2-ethylhexanol, because when used in PVC compounds, the C9 esters yield performance advantages over the C8 esters in higher performance, improved extraction resistance to water, lower emissions during processing, lower specific gravity, and low temperature flexibility. However, these products are slightly defensive to the C8 esters in that they require 1xc2x0 C.-3xc2x0 C. higher processing temperatures and slightly longer dry-blending times.
Although the C9 esters offer advantages over the C8 esters with lower emissions, the level of emission are often not acceptable for some end-uses. For products used in the interior passenger compartment for automobiles, manufacturers often develop specifications on the level of emissions or xe2x80x9cfogxe2x80x9d which can be released as the automobile sits in the sun. Currently, no C8 phthalate esters and no branched C9 phthalate meet specifications which require a minimal fog formation observed after 3 hours at 100xc2x0 C., in a fog testing apparatus. To meet these test performance criteria, phthalate esters of branched or linear C10 and C11 alcohols, phthalate esters of the more expensive linear C9 alcohols or esters of trimellitic anhydride must be used.
In accordance with Wadey et al., xe2x80x9cThe Nonyl Phthalate Ester and Its Use in Flexible PVCxe2x80x9d, Journal of Vinyl Technology, December 1990, Vol. 12, No. 4, pp. 208-211, there are currently known various di-nonyl, di-2-methyloctyl (alpha branched) phthalate esters varying in degree of branching which are not yet commercially available. These include moderately branched phthalate esters (Jayflex DINP), slightly branched (Palatinol N), highly branched (3,5,5-trimethyl hexyl phthalate type), and linear C9 phthalate (70% n-nonyl, 30% various alpha branched isomers).
It is known in the industry that typical branched C9 phthalates fail the automotive fogging specifications. The present inventors have demonstrated in the examples set forth hereafter that the novel branched C7-C 11 phthalate, trimellitate and adipate esters (e.g., branched C9 phthalate, trimellitate and adipate esters) of the present invention which are formed from a branched oxo C7-C11 oxo alcohols unexpectedly pass the fog test. The branched nature of these plasticizers will make them slightly more compatible than conventional Jayflex L9P, and thus yield even better performance in PVC compounds. These unique branched C7-C11 oxo phthalate, trimellitate and adipate esters have low fogging properties which are highly desirable for use in automotive interior applications.
Phthalate esters prepared from branched C7-C11 oxo alcohols according to the present invention produce a flexible PVC plasticizer which has all the performance advantages associated with conventional branched C9 phthalate esters, while dry-blending faster, i.e., process faster, than DOP. When compared to other known branched phthalate esters, the phthalate esters of branched C9 oxo alcohols according to the present invention provide improved efficiency, better low temperature performance, and lower emission release (i.e. fogging) during processing.
Additionally, the present inventors have discovered that trimellitate esters formed according to the present invention tend to dry-blend faster than Jayflex TINTM (triisononyl trimellitate prepared from 3 moles of C9 alcohol and 1 mole of trimellitic anhydride). They also tend to be more efficient. The trimellitate oxo esters according to the present invention may also replace TOTM (tri-2-ethyl hexyl trimellitate) in automotive instrument applications and in wire and cable formulations where conventional trimellitate esters have not been successful. Furthermore, because trimellitate oxo esters of the present invention have lower volatility, they will have a longer useful product life. Moreover, the trimellitate oxo esters could be used in fixture 125xc2x0 C. wire applications where low volatility, higher plasticizer efficiency, and improved processability are desired.
The present invention also provides many additional advantages that shall become apparent as described below.
The present invention includes a novel series of plasticizer esters and method for making such ester for use in the formulation of polyvinyl chloride (PVC), such as phthalates, adipates and trimellitates. The plasticizer esters according to the present invention are prepared by the reaction of at least one branched C7-C11 oxo alcohol prepared by hydroformylation from C6-C10 olefins comprising at least 50% methyl branching at the beta carbon with at least one acid and/or anhydride, in the presence of a catalyst.
The present invention also includes a process for preparing a plasticizer ester comprising: reacting a branched C7-C11 oxo alcohol prepared from C6-C10 olefins by hydroformylation with at least one acid and/or anhydride in the presence of a catalyst, wherein said olefins comprise at least 50% methyl branching at the beta carbon.
The present invention also includes a polyvinyl chloride resin composition comprising polyvinyl chloride and the plasticizer esters of the present invention and optionally, stabilizers, fillers and other well-known additives that are commonly used in the art. The polyvinyl chloride resin compositions can be used to prepare films, sheets or extruded, molded or cast products that are suitable for use in all areas of polyvinyl chloride applications.
Other and further objects, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the annexed drawings, wherein like parts have been given like numbers.